diff --git a/.gitea/workflows/render.yaml b/.gitea/workflows/render.yaml
index 81ae462..9f5f0fd 100644
--- a/.gitea/workflows/render.yaml
+++ b/.gitea/workflows/render.yaml
@@ -16,6 +16,8 @@ jobs:
       - name: Download java
         run: wget https://github.com/adoptium/temurin21-binaries/releases/download/jdk-21.0.3%2B9/OpenJDK21U-jre_x64_linux_hotspot_21.0.3_9.tar.gz
       - run: tar -xvzf OpenJDK21U-jre_x64_linux_hotspot_21.0.3_9.tar.gz
+      - name: install graphviz
+        run: apt install graphviz
       - name: render
         run: ./jdk-21.0.3+9-jre/bin/java -jar plantuml-1.2024.5.jar polycule.puml
       - uses: actions/upload-artifact@v4